Composite material having reduced degradation of pasty property

ABSTRACT

A composite material including silanated filler and mixed polymerizable monomer, having a stable pasty property which keeps well and has a consistent usability. A composite material containing a silanated filler, a polymerizable monomer, and a polymerization initiator, and may be produced by a process which includes in order of a mixed polymerizable monomer preparing step, a mixed polymerizable monomer preserving step, a composite material preparing step, a composite material preserving step, a composite material filling step, and a small quantity preserving container preserving step.

BACKGROUND

The present disclosure relates to a dental composite material used for afilling restoration, a prosthetic restoration, a temporary sealing, atemporary adhering, a prosthesis preparation, an adhesion, acementation, a crypt fissure sealing in the dental field, morespecifically, relates to a pasty composite material prepared by mixing asilanated filler and a polymerizable monomer, which is used for acomposite resin (including for a facing crown and for a restoration orthe like), a temporary sealing material, a temporary adhering material,a resin cement, an adhesive, a fissure sealant.

In the dental field, a composite material is prepared by mixing asilanated filler and a polymerizable monomer in the form of a paste. Thepasty composite material (the composite material in the form of a paste)is provided to dentists and dental technicians, which are the user ofthe composite material, in a packaging container filled with thecomposite material. Although the composite material may be blended withan adhesive monomer, a pigment, or the like, in accordance with thepurpose of use, the composite material is generally prepared in the formof a paste by mixing a silanated filler and a polymerizable monomer inthe appropriate amount, and then is filled in a packaging container.

It is difficult to stabilize a pasty property of the pasty compositematerial. For example, in the case where the composite material isfilled in a syringe container, the pasty property of the pasty compositematerial at an initial stage of discharging from the syringe containeris different from that at an end stage of discharging from the syringecontainer. Also, the pasty property of the pasty composite materialimmediately after production is different from that of the pastycomposite material preserved for a predetermined period.

The property of the composite material in which the pasty property isnot stable significantly varies according to the packaging containerused to package the composite material.

It is known that the pasty property and quality of the pasty compositematerial vary according to a mixing method or a mixing process in apaste production method. However, it has not been known that thecomposite material having a stable pasty property is obtained by aspecific mixing procedure or a specific mixing method.

In a conventional paste, bubbles caused by the mixing and/or a variationof a pasty property occur to cause non-uniform polymerization and thequality of final products varies greatly because of a large variation ofa flow value after preparation.

A consistent usability is required in a dental composite material bydentists and dental technicians.

BRIEF SUMMARY

Dentists and dental technicians are requesting a composite materialhaving a stably pasty property. The stably pasty property of a compositematerial is to keep a good and consistent usability.

The disclosure provides a composite material having a stably pastyproperty, especially provides a dental composite material that dentistsand dental technicians may use stably. For example, the method describedherein provides a stable the composite material.

To keep a stably pasty property has been required for a pasty compositematerial if the composite material is filled in various syringecontainers that are different in form.

To obtain a consistent pasty property from an initial period to a laterperiod in discharging from a syringe container has been required for apasty composite material filled in a syringe container. To obtain aconsistent pasty property from immediately after manufacturing to afterpreserving for a certain period of time has been required for a pastycomposite material.

It was impossible to obtain a pasty property that is the same at alltimes in a composite material discharged from a syringe container.

A composite material discharged from a syringe container includesunevenness and it was impossible to keep a stable pasty property.

A pasty property of a composite material filled in a syringe containerchanges according to a method of use including a continuous use, anintermittent use, and the case that an unused term exists etc., it wasimpossible to keep a stable pasty property.

A pasty property of a composite material changes according to a syringecontainer in which the composite material is filled. To obtain a stablepasty property has been required for a pasty composite material wheneach composite material is filled in different container.

The bubbles caused by mixing were observed in a composite materialfilled in a syringe container. Therefore, it has been necessary toperform additional work to removing the bubbles to a packaging processwhere the composite material is filled in a syringe container.

Generally, an inspection process has been included in a process ofmanufacturing a composite material. However, an appropriate time forperforming a inspection process for preparing stable a pasty compositematerial has not been known. Further, in order to prepare a stablecomposite material, it has been important to find an appropriate timefor performing the inspection process. The embodiments described hereincan prepare a composite material having a stable pasty property by usingan appropriate time for performing an appropriate inspection process ina manufacturing process.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete appreciation of the present invention and many of theattendant advantages thereof will be readily obtained as the samebecomes better understood by reference to the following detaileddescription when considered in connection with the accompanyingdrawings, wherein:

FIG. 1 is preparing condition, mixing condition, preserving conditionand evaluation result of mixed polymerizable monomer;

FIG. 2 is preparing condition, mixing condition, preserving conditionand evaluation result of composite material

FIG. 3 is Preparing condition, mixing condition, preserving conditionand evaluation result of composite material; and

FIG. 4 is fluidity (flow) test result and difference between present andlast time at small amount preservation container preservation.

DETAILED DESCRIPTION

Described herein is a composite material containing a silanated filler,a polymerizable monomer, and a polymerization initiator, and thecomposite material is produced by a process that comprises in order of:a mixed polymerizable monomer preparing step that includes a step ofmixing a polymerizable monomer and a polymerization initiator to preparea mixed polymerizable monomer, a mixed polymerizable monomer preservingstep that includes a step of preserving the mixed polymerizable monomerin a mixed polymerizable monomer preserving container, a compositematerial preparing step that includes a step of mixing the mixedpolymerizable monomer and a silanated filler to prepare a compositematerial, a composite material preserving step that includes a step ofpreserving the composite material in a composite material preservingcontainer, a composite material filling step that includes a step offilling the composite material into a small quantity preservingcontainer, a small quantity preserving container preserving step thatincludes a step of preserving the composite material in the smallquantity preserving container.

Also described herein is a composite material containing a silanatedfiller, a polymerizable monomer, and a polymerization initiator, and isproduced by a process that comprises in order of: a mixed polymerizablemonomer preparing step that includes a step of mixing a polymerizablemonomer and a polymerization initiator to prepare a mixed polymerizablemonomer, a composite material preparing step that includes a step ofmixing the mixed polymerizable monomer and a silanated filler to preparea composite material, a composite material filling step that includes astep of filling the composite material into a small quantity preservingcontainer, a small quantity preserving container preserving step thatincludes a step of preserving the composite material in the smallquantity preserving container, wherein; the composite material preparingstep includes a step of performing in order of a particulate fillerkneading step, a defoaming step after kneading the particulate filler, asilanated filler kneading step, and a defoaming step after kneading thesilanated filler.

The mixed polymerizable monomer preserving step preferably includes amixed polymerizable monomer evaluation step. Performing the mixedpolymerizable monomer evaluation step in the mixed polymerizable monomerpreserving step contributes a stable supply of the composite material.

Also, the composite material preserving step preferably includes acomposite material evaluation step. Performing the composite materialevaluation step in the composite material preserving step contributes toa stable production of the composite material.

Further, the small quantity preserving container is preferably a syringecontainer. The composite material becomes stable by preserving in apredetermined period in the syringe container, which is a container usedby an end user.

The present disclosure also provides for a composite material containinga silanated filler, a polymerizable monomer, and a polymerizationinitiator, and is produced by a process which comprises in order of amixed polymerizable monomer preparing step, a mixed polymerizablemonomer preserving step, a composite material preparing step, acomposite material preserving step, a composite material filling step,and a small quantity preserving container preserving step.

The mixed polymerizable monomer preparing step includes a step ofcharging a polymerization initiator into a polymerizable monomer in amixing container, and mixing the polymerizable monomer and thepolymerization initiator at a mixing temperature of 1-60° C. for amixing period of 1 minute-24 hours to prepare a mixed polymerizablemonomer.

The mixed polymerizable monomer preserving step includes a step ofpreserving 1-50 liters of mixed polymerizable monomer prepared in themixed polymerizable monomer preparing step at preserving temperature of1-23° C. for a preserving period of 10 days-1.5 years.

The composite material preparing step includes a step of performing akneading step, and a defoaming step, at the ratio of 0.1-9 parts byweight of the silanated filler based on 1 part by weight the mixedpolymerizable monomer, which includes a step of charging the silanatedfiller into the mixed polymerizable monomer.

When the composite material contains particulate filler, the materialpreparing step includes a step of performing in order of a particulatefiller kneading step, a defoaming step after kneading the particulatefiller, a silanated filler kneading step, and a defoaming step afterkneading the silanated filler.

The particulate filler kneading step includes a step of kneading themixed polymerizable monomer and a particulate filler at a kneadingtemperature of 5-60° C. for a kneading period of 5-30 minutes aftercharging the particulate filler into the mixed polymerizable monomer.The defoaming step after kneading the particulate filler includes a stepof defoaming from the mixed polymerizable monomer and the particulatefiller at 5-200 Torr for a defoaming period of 5-30 minutes.

The silanated filler kneading step includes a step of kneading the mixedpolymerizable monomer, the particulate filler, and a silanated filler ata kneading temperature of 5-60° C. for a kneading period of 5-40 minutesafter charging the silanated filler. The defoaming step after kneadingthe silanated filler includes a step of defoaming from the mixedpolymerizable monomer, the particulate filler and the silanated fillerat 5-200 Torr for a defoaming period of 5-30 minutes to prepare acomposite material.

The composite material preserving step includes a step of preserving the1-8 liters of composite material prepared in the composite materialpreparing step at preserving temperature of 1-25° C. for a preservingperiod of 10 days-1.5 years.

The composite material filling step includes a step of filling thecomposite material extruded from a nozzle using a filling machine into asmall quantity preserving container having 1-50 cc of volume.

The small quantity preserving container preserving step includes a stepof preserving the composite material in the small quantity preservingcontainer at a preserving temperature of 1-40° C. for a preservingperiod of 50 days-5 years.

In addition to the above described steps, a defective product may befound by performing evaluation steps, thereby preventing manufacturingof a defective product. Further, these evaluation steps are importantfor obtaining a composite material having a stable pasty property.

The mixed polymerizable monomer evaluation step performed in the mixedpolymerizable monomer preserving step is a step of performing at leastone of a differential scanning calorimetry (DSC) test, a hardening test,and/or a fluidity test and preferably performing all of a differentialscanning calorimetry (DSC) test, a hardening test, and a fluidity test.

The composite material evaluation step performed in the compositematerial preserving step is a step of performing at least one of adifferential scanning calorimetry (DSC) test, a hardening test, and/or afluidity test and preferably performing all of a differential scanningcalorimetry (DSC) test, a hardening test, and a fluidity test.

The final evaluation step performed in the small amount preservingcontainer preserving step is a step of performing at least one of adifferential scanning calorimetry (DSC) test, a hardening test, and/or afluidity test and preferably performing all of a differential scanningcalorimetry (DSC) test, a hardening test, and a fluidity test.

The present disclosure provides a composite material discharged from thesyringe container, which may be used under a consistent operability,includes no variation, and may keep a property stably at an early stage,at a middle stage, and at an end stage.

A pasty property of a composite material filled in a syringe containerchanges according to the method of use including a continuous use, anintermittent use, and the case that an unused term exists etc., and itwas impossible to keep a stable pasty property.

In any case of a continuous use, an intermittent use, and the case thatan unused term exists etc., the composite material discharged from thesyringe container may be used under a consistent operability.

Applying a pressure to the composite material in the container meansthat the composite material in static condition is pressurized to becomethe pasty composite material having reduced thixotropy. Then, thecomposite material is discharged from the discharging port for releasingthe pressure. According to the quantity of the force applied to thecomposite material, the thixotropy gradually decreases.

Once the thixotropy of the composite material decreases, even if theforce such as pressure is released, the state that the thixotropydecreases is kept for a while. The thixotropy of the composite materialincreases by continuing the static condition. When the force such aspressure is applied to the composite material of which the thixotropy isnot completely reduced, the thixotropy is completely reduced more. Inthe conventional composite material, it is difficult to control thethixotropy and to have a uniform pasty property of the dischargedcomposite material. The present disclosure solves the conventionalproblems. The present disclosure provides a composite material which maykeep for a fixed amount of time, and has a uniformly pasty property thatthe thixotropy decreases after discharging from the container.

Further, bubbles mixing in the composite material when filling to thesmall preserving container are prevented. The composite material ispreserving in the preserving container in the composite materialpreserving step. The preserving amount of the composite materialpreserving container is larger than that of the small amount preservingcontainer at the same time. This prevents the paste from a propertychange at the initial stage because of a decreasing surface area of thepaste that contacts the outside. However, it is difficult to prevent thepaste from “solidification,” which is a property change at the surface.In a preferred embodiment, the composite material is filled in the smallquantity preserving container before “solidification.” Therefore, in apreferred embodiment, the composite material wherein the property changeat the initial stage is prevented, and bubbles mixing in the compositematerial is prevented.

The composite material is charged into the filling machine from thepreserving container in the composite material preserving step, and iscontinuously filled into the small amount preserving container. When theremaining amount of the composite material in the filling machinebecomes low, the composite material is replenished from the preservingcontainer of the composite material preserving step. This replenishingof the composite material from the preserving container of the compositematerial preserving step causes many bubbles mixing into the compositematerial resulting from the solidification of the surface. However, thecomposite material described herein reduces the bubbles mixing into thecomposite material during replenishing of the composite material.

Performing an inspection step in the process of preparing the compositematerial easily contributes a stable production of the compositematerial. Although performing many inspection steps contributes to astable production of the composite material, excessive inspection stepsconsumes the composite material and increases the number of man hoursfor production. An appropriate number of inspection steps and anappropriate timing of the inspection steps were found. As a result, adefective product may be found to prevent manufacturing the defectiveproduct and to prepare the composite material efficiently.

By performing the particulate filler kneading step, a defoaming stepafter kneading the particulate filler, the silanated filler kneadingstep, and a defoaming step after kneading the silanated filler, thethixotropy of the composite material becomes stable and obtains acomposite material having a uniformly pasty property.

A filler before silanation used in the embodiments is not specificallylimited, and a filler known in the art such as an inorganic fillerand/or an organic filler and/or an organic-inorganic composite filler,for example, may be used without restriction. The grain shape of thefiller before silanation may be any shape like a sphere, a massive, aneedle, a plate, a fracture, a scale, etc., and is not specificallylimited. For obtaining a greater stability of the paste, the fillerbefore silanation preferably has a sphere shape. The degree ofcircularity of the filler before silanation ranges from 0.7 to 1.0,preferably from 0.9 to 1.0, and more preferably from 0.95 to 1.00.

The degrees of circularity are determined by taking an image of theparticles with a light microscope or a scanning electron microscope(SEM) and analyzing the image with an image analyzer. The number offillers to be analyzed per sample may be 50 or more. The degrees ofcircularity are determined based on boundary lengths and area of thefillers before silanated. The degree of circularity e=(4*.π.*S)/(L²) iscalculated with boundary lengths (L) and area (S) of the fillers beforesilanation, which are obtained by analyzing the image.

Specific examples of the inorganic filler include quartz, amorphoussilica, aluminum silicate, aluminum oxide, titanium oxide, zirconiumoxide, various types of glass (including glass obtained by a meltingmethod, synthetic glass obtained by a sol-gel method, and glassgenerated by a gas phase reaction), calcium carbonate, talc, kaoline,clay, mica, aluminum sulfate, calcium sulfate, barium sulfate, calciumphosphate, hydroxyapatite, silicon nitride, aluminum nitride, titaniumnitride, silicon carbide, boron carbide, calcium hydroxide, strontiumhydroxide, and zeolite. Among these, aluminosilicate glass,borosilicate, aluminoborate, and boroaluminosilicate glass containing aheavy metal such as sodium, strontium, barium, and lanthanum and/orfluorine are preferable. The average grain size of the inorganic filleris not specifically limited, and is preferably in the range of 0.5 to 10μM, more preferably in the range of 0.7 to 5 μM.

Ultrafine particle inorganic fillers such as aerosil generated by a gasphase method or particles of silica-zirconia oxide generated from asolution in a sol-gel reaction may also be used. Cohesive inorganicfillers obtained by agglomerating such ultrafine particles may also beused. Cohesive inorganic fillers are crushing during kneading. Crushedinorganic fillers having 1 nm to 300 nm particle diameters areclassified as an ultrafine particulate inorganic filler, and crushedinorganic fillers not having 1 nm to 300 nm particle diameter areclassified as an inorganic filler.

The average particle size of ultrafine particulate inorganic filler isfrom 1 nm to 300 nm. The ultrafine particulate inorganic filler ispreferably, without any limitation, colloidal silica (trade names:Aerosil R972, Aerosil 200, Aerosil 380, Aerosil 50 (Nippon Aerosil Co.,Ltd. 5-50 nm)).

The organic filler can be obtained by polymerizing a monomer having apolymerizable group, and the type of the organic filler is notspecifically limited. Specific examples of the organic filler includeunsaturated aromatics such as styrene, α-methylstyrene, halogenatedstyrene, and divinylbenzene; unsaturated esters such as vinyl acetateand vinyl propionate; unsaturated nitriles such as acrylonitrile; andsubstances obtained by (co)polymerizing a single or a plurality ofmonomers having a polymerizable group such as butadiene and isoprene.Substances obtained by polymerizing the monomers having a polymerizablegroup discussed earlier known in the dental field are particularlypreferable. The method of manufacturing the organic filler is notspecifically limited, and may be any method in which the monomers havinga polymerizable group is subjected to an emulsion polymerization, asuspension polymerization, a dispersion polymerization, or the like, andmay be a method in which a polymer bulk generated in advance ispulverized. Organic-inorganic composite fillers in which inorganicparticles are contained in an organic polymer may also be used. Theinorganic particles to be contained in the organic polymer are notspecifically limited, and those known in the art may be used. Examplesof the inorganic particles include particles of the inorganic fillersdiscussed above. The method of manufacturing the organic-inorganiccomposite filler is also not specifically limited, and any method may beused. Examples of the method include a method in which the surfaces ofthe inorganic particles are microencapsulated or grafted with theorganic substance, a method in which the inorganic particles aresubjected to a radical polymerization after a polymerizable functionalgroup or a polymerization initiating group is introduced into thesurfaces of the inorganic particles, and a method in which a polymerbulk containing inorganic particles generated in advance is pulverized.

The average grain size of the organic filler or the organic-inorganiccomposite filler is preferably in the range of 1 to 100 μm, morepreferably 3 to 50 μm, further more preferably 5 to 30 μm. Theinorganic, organic, and organic-inorganic composite fillers may be usedsingly or in combination of several kinds thereof.

After the surfaces of the particles of the filler, such as theinorganic, organic, or organic-inorganic composite filler, are treatedby a method known in the art, the filler can be used for a compositematerial. The surface treatment may be performed using a surfactant,fatty acid, organic acid, inorganic acid, a silane coupling agent, atitanate coupling agent, polysiloxane, or the like, for example. Apreferable surface treatment method improves the wettability between theresin component and the surface of the filler and imparts superiorproperties to the composite material, and can be selected as appropriateaccording to the required properties. The surface of the filler may besubjected, without restriction, to a surface treatment performed using aspecial surface treatment agent and/or by a special surface treatmentmethod for the purpose of increasing the functionality of the filler.

A silanated filler provided by a silanation step in which a filler istreated with a silane coupling agent is preferably used. Further, thesilanated filler is preferably provided through a silanated fillerpreserving step in which a silanated filler is preserved for apredetermined period.

The silanation step includes a step of preparing a silane treatmentliquid containing 1-40% of silane coupling agent, and 60-99% of organicsolvent and/or water, and a step of treating a filler with the silanetreatment liquid. The filler and the silane treatment liquid are chargedinto a treatment container and the filler is silanated at a treatmenttemperature of 1-60° C. for a treatment period of 1 minute-24 hours. Thesilane treatment liquid is charged in a ratio of 1-15 volume % based onthe volume of the filler. As a result of silanation, the silanatedfiller may be a slurry. The silane treatment liquid is preferablycharged by spraying or dripping.

An aggregate is provided by drying the treated material at a dryingtemperature of 60-200° C. for a drying period of 1-120 hours. Thesilanated filler is provided by crushing the aggregate.

The silane treatment liquid preferably contains 5-30% of silane couplingagent, 50-70% of organic solvent and/or 0.5-25% of water.

As the silane coupling agent, there can be preferably used, notparticularly limited to, methyltrimethoxysilane, methyltriethoxysilane,methyltrichlorosilane, dimethyldichlorosilane, trimethylchlorosilane,hexamethyldisilazane, vinyltrimethoxysilane, vinyltriethoxysilane,vinyltrichlorosilane, vinyltriacetoxysilane,vinyltris((3-methoxyethoxy)silane,γ-methacryloyloxypropyltrimethoxysilane,γ-methacrloyloxypropyltris(β-methoxyethoxy)silane,γ-chloropropyltrimethoxysilane, γ-chloropropylmethyldimethoxysilane,γ-glycidoxypropyltrimethoxysilane,γ-glycidoxypropylmethyldiethoxysilane,β-(3,9-epoxycyclohexyl)ethyltrimethoxysilane,N-phenyl-γ-aminopropyltrimethoxysilane and hexamethyldisilazane.Particularly preferably are methyltrichlorosilane,dimethyldichlorosilane and hexamethyldisilazane.

An organic solvent is preferably a volatile water-soluble organicsolvent. As the volatile water-soluble organic solvent, there can beexemplified methanol, ethanol, n-propanol, isopropyl alcohol, acetone,methyl ethyl ketone and the like. As required, these organic solventscan be used in a plural kinds being mixed together. By taking toxicityto a living body into consideration, it is desired to use ethanol,isopropyl alcohol and acetone.

The silanated filler preserving step includes a step of preserving asilanated filler for a preserving period of 30-600 days. When apreserving period is short, matching with resin deteriorates. Therefore,it is difficult to prepare a smooth paste, and it is difficult toprepare a stable paste.

When a preserving period lasts for a long term, the effect of the silanecoupling agent fades and it is difficult to prepare a stable paste.

The silanated filler is preserved in a hermetic container. The volume ofthe container is 10-50 liters. The container is preferably made ofpolyethylene and formed into bag-shape.

The preserving temperature is at 1-50° C. and is preferably at 5-25° C.Preserving at high temperatures obstructs the effect of the silanecoupling agent.

A proportion of the silanated filler in a composite material may beoptionally selected depending upon a material property required for acomposite material. An filling amount of low-viscous materials such assealants, bonding materials, primers, tooth surface treating agents,opacifying agents and cements generally used in the dental field shouldbe set at a relatively small level since higher fluidity required asmaterial property is required for these materials. Therefore, the amountis preferably in a range of 5.0-80.0 parts by weight, more preferably ina range of 30.0-70.0 parts by weight relative to the whole component ofthe composite material. In addition, a filling amount of high-viscousmaterials such as a composite resin and a veneer crown resin should beset at a relatively high level since, as the required material property,such the shapability is required that does not cause deformation aftershape adjustment. Accordingly, the amount is preferably in a range of50.0-98.0 parts by weight, more preferably in a range of 75.0-98.0 partsby weight relative to the whole component of a composite material.

The polymerizable monomer used in the embodiments may be, without anylimitation, known monofunctional or multifunctional polymerizablemonomers that are generally used for composite material. Thepolymerizable monomers are preferably those having an acryloyl groupand/or a methacryloyl group.

Examples of polymerizable monomers having no acidic group include:

monofunctional monomers (non-crosslinkable monomers), e.g.,(meth)acrylic acid esters such as methyl(meth)acrylate,ethyl(meth)acrylate, butyl(meth)acrylate, hexyl(meth)acrylate,tetrahydrofurfuryl(meth)acrylate, 2-hydroxyethyl(meth)acrylate,grycidyl(meth)acrylate, lauryl(meth)acrylate, cyclohexyl(meth)acrylate,benzil(meth)acrylate, allyl(meth)acrylate, 2-ethoxyethyl(meth)acrylate,methoxy polyethylene glycol(meth)acrylate, glycerol(meth)acrylate andisobornyl(meth)acrylate; silane compounds such as.gamma.-(meth)acryloyloxypropyltrimethoxysilane and.gamma.-(meth)acryloyloxypropyltriethoxysilane; nitrogen-containingcompounds such as 2-(N,N-dimethylamino)ethyl(meth)acrylate,N-methylol(meth)acrylamide and diacetone(meth)acrylamide,

aromatic bifunctional monomers (crosslinkable monomers), e.g.,2,2-bis(4-(meth)acryloyloxyphenyl)propane,2,2-bis(4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl)propane,2,2-bis(4-(meth)acryloyloxyethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxydiethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxytetraethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxypentaethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxydipropooxyphenyl)propane,2(4-(meth)acryloyloxyethoxyphenyl)-2-(4-(meth)acryloyloxydiethoxyphenyl)propane,2-(4-(meth)acryloyloxydiethoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane,2-(4-(meth)acryloyloxydipropoxyphenyl)-2-(4-(meth)acryloyloxytriethoxyphenyl)propane,2,2-bis(4-(meth)acryloyloxydipropoxyphenyl)propane and2,2-bis(4-(meth)acryloyloxyisopropoxyphenyl)propane,

aliphatic bifunctional monomer (crosslinkable monomers), e.g.,2-hydroxy-3-acryloyloxypropylmethacrylate, hydroxypivalic acidneopentylglycol di(meth)acrylate, ethylene glycol di(meth)acrylate,diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate,butylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate,neopentyl glycol di(meth)acrylate, propylene glycol di(meth)acrylate,1,3-butanediol di(meth)acrylate, 1,4-butanediol(meth)acrylate,1,6-hexanediol di(meth)acrylate, and glycerin di(meth)acrylate,trifunctional monomer (crosslinkable monomers), e.g.,

trimethylolpropane tri(meth)acrylate, treimethylolethanetri(meth)acrylate, trimethylolmethane tri(meth)acrylate andpentaerythritol tri(meth)acrylate,

tetrafunctional monomer (crosslinkable monomers), e.g., pentaerythritoltetra(meth)acrylate and ditrimethylolporpane tetra(meth)acrylate.

Examples of urethane-based polymerizable monomers may includedi(meth)acrylates having a bifunctional or trifunctional ormore-functional urethane linkage that are derived from an adduct of apolymerizable monomer having a hydroxy group such as2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate and3-chloro-2-hydroxypropyl(meth)acrylate, and a diisocyanate compound suchmethylcyclohexane diisocyanate, methylene bis(4-cyclohexyl isocyanate),isophorone diisocyanate, diisocyanate methylbenzene and4,4-diphenylmethane diisocyanate.

In addition to the aforementioned (meth)acrylate-based polymerizablemonomers, other polymerizable monomers, for example, a monomer, anoligomer or a polymer having at least one polymerizable group in themolecule may be used for polymerizable monomers of the compositematerial if desired. The polymerizable monomers other than the(meth)acrylate-based polymerizable monomers may have a substituent suchas an acidic group and a fluoro group in the molecule. In theembodiments, the polymerizable monomer is not necessarily of a singlecomponent, and may be a mixture of a plurality of polymerizablemonomers. If the viscosity of the polymerizable monomer at roomtemperature is extremely high, or if the polymerizable monomer is solid,the polymerizable monomer is preferably combined with a polymerizablemonomer with low viscosity to be used as a mixture of the polymerizablemonomers. The combination is not limited to a combination of two kinds,and may be a mixture of three or more kinds.

The polymerizable monomers of the composite material may include onlymonofunctional polymerizable monomers, and may additionally includepolyfunctional polymerizable monomers. A preferred polymerizablemonomers may include an aromatic bifunctional polymerizable monomer andan aliphatic bifunctional polymerizable monomer. More preferably, thepolymerizable monomers may includes2,2-bis(4-(3-methacryloyloxy-2-hydroxypropoxy)phenyl)propane (Bis-GMA)and triethylene glycol dimethacrylate (TEGDMA).

In the embodiments, the polymerizable monomers may include polymerizablemonomers containing an acid group such as phosphoric acid group,carboxylic acid group, phosphonic acid, sulfonic acid group or the likein the molecule as a part or the whole of the polymerizable monomers sothat the composite material can adhere to the teeth substance and anonprecious metal. In order to enhance the property to adhere a preciousmetal, the polymerizable monomers may include a polymerizable monomercontaining a sulfur atom in the molecule.

The polymerizable monomers discussed above may include carboxylilc acidgroup-containing polymerizable monomers, e.g., (meth)acrylic acid,1,4-di(meth)acryloyloxyethyl-pyromellitic acid,6-(meth)acryloyloxynaphtalene-1,2,6-tricarboxylic acid,N-(meth)acryroyl-p-aminobenzoic acid, N-(meth)acryroyl-5-aminosalicylicacid, 4-(meth)acryroyloxyethyltrimellic acid and anhydride thereof,4-(meth)acryroyloxybutyltrimellic acid and anhydride thereof,2-(meth)acryroyloxybenzoic acid, β-(meth)acryroyloxyethyl hydrogensuccinate, β-(meth)acryroyloxyethyl hydrogen maleate,11-(meth)acryloyloxy-1,1-undecanedicarboxylic acid and p-vinylbenzoicacid; phosphate group-containing monomers, e.g.,2-(meth)acryloyloxyethyl hydrogen phosphate, 3-(meth)acryloyloxypropyldihydrogen phosphate, 10-(meth)acryloyloxydecyl hydrogen phosphate,bis(2-(meth)acryloyloxyethyl)dihydrogen phosphate and2-(meth)acryloyloxyphenyl hydrogen phosphate; sulfonic group-containingmonomers, e.g., 2-(meth)acrylamide-2-methylpropanesulfonic acid,4-(meth)acryloyloxybenzenesulfonic acid and3-(meth)acryloyloxypropanesulfonic acid; sulfur atom-containingmonomers, e.g., (meth)acrylate having a triazinethiol group,(meth)acrylate having a mercapto group, (meth)acrylate having apolysulfide group, (meth)acrylate having a thiophosphate group,(meth)acrylate having a disulfide cyclic group, (meth)acrylate having amercaptodithiazole group, (meth)acrylate having a thiouracil group and(meth)acrylate having a thiirane group. These polymerizable monomers maybe used alone or in mixture of two or more kinds.

A known radical generator may be used as a polymerization initiator inthe embodiments. Polymerization initiators are generally classified intochemical polymerization initiators that initiates polymerization bymixing the same with the monomers upon use, thermal polymerizationinitiators that initiates polymerization by heating or warming thecomposition, and photoinitiators that initiates polymerization by lightirradiation.

Among such polymerization initiators, examples of chemicalpolymerization initiators may include redox type polymerizationinitiator systems comprising an organic peroxide/an amine compound or anorganic peroxide/an amine compound/a sulfinic acid salt, or an organicperoxide/an amine compound/a borate compound, and organometal typeinitiator systems that initiate polymerization by reacting with oxygenor water.

Examples of the aforementioned organic peroxides may includebenzoylperoxide, parachlorobenzoylperoxide, 2,4-dichlorobenzoylperoxide, acetyl peroxide, lauroyl peroxide, tertiary-butyl peroxide,cumene hydroperoxide, 2,5-dihydroperoxy-2,5-dimethylhexane, methyl ethylketone peroxide, and tertiary-butyl peroxide benzoate.

Examples of the aforementioned amine compounds may include a secondaryor tertiary amine in which an amine group is bound to an aryl group, andparticular examples thereof are p-N,N-dimethyltoluidine,N,N-dimethylaniline, N-β-hydroxyethylaniline,N,N-di(β-hydroxyethyl)aniline, p-N,N-di(β-hydroxyethyl)toruidine,N-methylaniline, and p-N-methyltoluidine.

Examples of the aforementioned sulfuric acid salts may include sodiumbenzenesulfinate, lithium benzenesulfinate, and sodiump-toluenesulfinate.

Examples of the aforementioned borate compounds include,trialkylphenylboron, and a sodium salt, a lithium salt, a potassiumsalt, a magnesium salt, a tetrabutyl ammonium salt and a tetramethylammonium salt of trialkyl(p-fluorophenyl)boron (wherein the alkyl groupis n-butyl group, n-octyl group, n-dodecyl group or the like).

Examples of the aforementioned organometal type polymerizable initiatorsmay include organic boron compounds such as triphenylborane,tributylborane, and a partial oxide of tributylborane.

Azo compounds such as azobisisobutyronitrile, methyl azobisisobutyrateand azobiscyano valeric acid may be used as a thermal polymerizationinitiator used in the embodiments in addition to the aforementionedorganic peroxide.

The photoinitiator used in the embodiments may be a photosensitizer. Thephotosensitizer may be used alone or in combination with aphotopolymerization promotor. Examples of the aforementionedphotosensitizers may include α-diketones such as benzil, camphorquinone,α-naphtil, acetonaphtone, p,p′-dimethoxybenzil,p,p′-dichlorobenzylacetyl, pentadione, 1,2-phenanthrenquinone,1,4-phenanthrenquinone, 3,4-phenanthrenquinone, 9,10-phenanthrenquinoneand naphthoquinone; benzoin alkyl ethers such as benzoin, benzoin methylether and benzoin ethyl ether; thioxanthones such as thioxanthone,2-chlorothioxanthone, 2-methylthioxanthone, 2-isopropylthioxanthone,2-methoxythioxanthone, 2-hydroxythioxanthone, 2,4-diethylthioxanthoneand 2,4-diisopropylthioxanthone; benzophenones such as benzophenone,p-chlorobenzophenone and p-methoxybenzophenone; acylphosphineoxides suchas 2,4,6-trimethylbenzoyl diphenylphosphineoxide andbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphineoxide;α-aminoacetophenones such as2-benzyl-dimethylamino-1-(4-morpholinophenyl)-butanone-1,2-benzyl-diethyl-amino-1-(4-morpholinophenyl)propanone-1;ketals such as benzyldimethylketal, benzyldiethylketal andbenzyl(2-methoxyethylketal); titanocenes such asbis(cyclopentadienyl)-bis[2,6-difluoro-3-(1-pyrolyl)phenyl]titanium,bis(cyclopentadienyl)-bis(pentanefluorophenyl)titanium andbis(cyclopentadienyl)-bis(2,3,5,6-tetrafluoro-4-disiloxyphenyl)-titanium.

Examples of the aforementioned photopolymerization promotors may includetertiary amines such as N,N-dimethylaniline, N,N-diethylaniline,N,N-di-n-butylaniline, N,N-dibenzylaniline, p-N,N-dimethyl-toluidine,m-N,N-dimethyltoluidine, p-N,N-diethyltoluidine,p-bromo-N,N-dimethylaniline, m-chloro-N,N-dimethylaniline,p-dimethylaminobenzaldehyde, p-dimethylaminoacetophenone,p-dimethylaminobenzoic acid, p-dimethylaminobenzoicacid ethyl ester,p-demtethylaminobenzoic acid amino ester, N,N-dimethylanthranilic acidmethyl ester, N,N-dihydroxyethylaniline, p-N,N-dihydroxyethyl-toluidine,p-dimethylaminophenylalcohol, p-dimethylaminostyrene,N,N-dimethyl-3,5-xylidine, 4-dimethylaminopyridine,N,N-dimethyl-α-naphthylamie N,N-dimethyl-β-naphthylamine, tributylamine,tripropylamine, triethylamine, N-methyldiethanolamine,N-ethyldiethanolamine, N,N-dimethylhexylamine, N,N-dimethyldodecylamine,N,N-dimethylstearylamine, N,N-dimethylaminoethyl methacrylate,N,N-diethylaminoethyl methacrylate and 2,2′-(n-butylimino)diethanol;secondary amines such as N-phenylglycine; barbituric acids such as5-butylbarbituric acid and 1-benzyl-5-phenylbarbituric acid; tincompounds such as dibutyltin diacetate, dibutyltin dilaurate, dioctyltindilaurate, dioctyltin diperacetate, dioctyltin bis(mercaptoacetic acidisooctyl ester) salt and tetramethyl-1,3-diacetoxydistannoxane; aldehydecompounds such as laurylaldehyde and terephthalaldehyde;sulfur-containing compounds such as dodecylmercaptan,2-mercaptobenzooxazole, 1-decanethiol and thiosalicylic acid.

The composite material of the present invention may further include anoxycarboxylic acid such as citric acid, maleic acid, tartaric acid,glycolic acid, gluconic acid, α-oxyisobutyric acid, 2-hydroxypropioicacid, 3-hydroxybutanoic acid, 4-hydroxybutanoic acid, anddimethylolpropioic acid to improve the photopolymerization promotingability.

Those polymerization initiators used in the embodiments may be usedalone or as a mixture of two or more thereof. In addition, thesepolymerization initiators may be used in combination irrespective of thepolymerization form and the kind of polymerization initiators. Theamount of a polymerization initiator to be added may be appropriatelydetermined depending upon the use. In general, the amount may beselected from a range of 0.1-10 parts by weight based on a polymerizablemonomer.

The polymerization initiator is preferably a photopolymerizationinitiator. The composite material that comprises a photopolymerizationinitiator is relatively easy to be polymerized without substantial airbubble entrainment. The photopolymerization initiator is preferably acombination of an α-diketone and a tertiary amine and more preferably, acombination of camphorquinone with an aromatic amine having an aminogroup directly bound to the benzene ring such as ethylp-N,N-dimethylaminobenzoate or with an aliphatic amine having a doublebond in the molecule such as N,N-dimethylaminoethyl methacrylate. Thecomposite material, in embodiments, may comprise, depending upon theuse, a sensitizing pigment such as coumalin, cyanine, and thiazine; alight acid generator which produces Broensted acid or Lewis acid bylight irradiator such as a s-triazine derivative substituted with ahalomethyl group or diphenyl iodonium salt compound; quaternary ammoniumhalides; and transition metal compound.

The composite material according to embodiments is prepared by mixing asilanated filler, a polymerizable monomer, and a polymerizationinitiator.

The composite materials may be colored with a coloring pigment inaccordance with a product property. The coloring pigments are classifiedinto inorganic pigments and organic pigments. Examples of inorganicpigments may include chromates such as chrome yellow, zinc yellow andbarium yellow; ferrocyanides such as Prussian blue; sulfides such asvermilion, cadmium yellow, zinc sulfide, antimony white and cadmium red;sulfates such as barium sulfate, zinc sulfate and strontium sulfate;oxides such as zinc white, titanium white, blood red, black iron oxideand chromium oxide; hydroxides such as aluminum hydroxide; silicatessuch as calcium silicate and ultramarine; and carbons such as carbonblock and graphite. Examples of organic pigments may include nitorosopigments such as Naphthol Green B and Naphthol Green Y; nitoro pigmentssuch as Naphthol S and Lithol Fast Yellow 2G; insoluble azo pigmentssuch as Permanent Red 4R, Brilliant Fast Scarlet, Hanza Yellow andBenzidine Yellow; poorly-soluble azo pigments such as Lithol Red, LakeRed C and Lake Red D; soluble azo pigments such as Brilliant Caramine6B, Permanent Red F5R, Pigment. Scarlet 3B and Bordeaux 10B;phthalocyanine pigments such as Phthalocyanine Blue, PhthalocyanineGreen and Sky Blue; basic dye pigments such as Rhodamine Lake, MalachiteGreen Lake and Methyl Violet Lake; and acidic dye pigments such asPeacock Blue Lake, Eosin Lake and Quinoline Yellow Lake. These pigmentsmay be used alone or in combination of two or more thereof. In anembodiment, the coloring pigment is preferably an inorganic pigment,preferably titanium white, blood red, black iron oxide or yellow ironoxide.

The composite material described herein may comprise an ultravioletabsorbing agent such as 2-hydroxy-4-methylbenzophenone; polymerizationinhibitors such as a hydroquinone, a hydroquinone monomethyl ether,2,5-di(tertiary-butyl)-4-methylphenol, and butyrated hydroxyltoluene(BHT); an anti-discoloring agent; an antimicrobial agent; and the otherconventional known additives. The composite material may be packed in asingle package, or divided into two packs or the other type packages.The package of the composite material may be determined depending uponthe kind of polymerization initiator or the use.

The effect of the composite material is provided by a process thatcomprises at least in order of a mixed polymerizable monomer preparingstep, a mixed polymerizable monomer preserving step, a compositematerial preparing step, a composite material preserving step, acomposite material filling step, and a small quantity preservingcontainer preserving step.

Hereinafter, each process will be sequentially described.

A mixed polymerizable monomer preparing step includes at least a step ofmixing a polymerizable monomer and a polymerization initiator to preparea mixed polymerizable monomer, but the method of mixing is notparticularly limited. It is necessary that a mixed polymerizable monomerprepared in the mixed polymerizable monomer preparing step is in auniform state after mixing. Therefore, it is necessary to mix so thatthere are no remainders such as a polymerization initiator. Preferably,a mixed polymerizable monomer preparing step does not include adefoaming step. A defoaming step is a step of defoaming air bubbles byreducing the pressure below the atmospheric pressure after mixing, whichis often performed at atmospheric pressure. Performing a defoaming stepmay deteriorate a polymerizable monomer, causes a reduction of thecharacteristic of a physical property, and some polymerizable monomersmay harden.

Further, it is necessary to charge a polymerization initiator into amixed polymerizable monomer. To charge a polymerization initiator into amixed polymerizable monomer causes a reduction of the characteristic ofa physical property and some polymerizable monomers may be harden.Therefore, an excessive amount of a polymerization initiator cannot bemixed.

A mixing volume of the mixed polymerizable monomer is 1-50 liters perbatch and is preferably 5-11 liters per batch. When the mixing volume issmall, not only a production process becomes longer but also a stableproduction of a mixed polymerizable monomer becomes difficult. When amixing volume is large, a polymerizable monomer often deteriorates andthe stability of the properties is affected.

A blender used in the method described in the embodiments is notspecifically limited, and is preferably a mixer that mixes apolymerizable monomer and a polymerization initiator in a mixingcontainer with a blade. More preferably, a blender is a tumbler mixerthat mixes a polymerizable monomer and a polymerization initiator byrotation or swing a mixing container. A deterioration of the contents inthe blender may be reduced by using a tumbler mixer. Although the mixingperiod is varied according to the blender, the mixing period ispreferably for 1 minute-24 hours, is more preferably for 15 minutes-10hours. The mixing temperature is at 1-60° C., preferably at 5-30° C.

When a polymerization initiator used in the composite material is achemical polymerization initiator, low temperature mixing is preferredand the mixing temperature is at 5-10° C.

During the mixing in this step, an additive agent such as apolymerization inhibitor, an antitarnish agent, an antimicrobe agent,and an ultraviolet absorber is preferably mixed at the same time. Thisprevents the deterioration of the composite material and contributes tothe stability of the composite material.

A permeability of a mixed polymerizable monomer is preferably 80-100%.When a composite material is used as a dental material, a stable colorreproducibility is required even though a composite material is coloredwith coloring materials, and the variations in color between lots becomea problem. Stable color tone stability is obtained as a permeability ofthe mixed polymerizable monomer is high.

A mixed polymerizable monomer preserving step includes a step ofpreserving a mixed polymerizable monomer prepared in the mixedpolymerizable monomer preparing step. A mixed polymerizable monomer ispreserved in a mixed polymerizable monomer preserving container. Thevolume of preserved mixed polymerizable monomer is 1-50 liters,preferably 5-11 liters.

When a tumbler mixer is used in the mixed polymerizable monomerpreparing step, the tumbler mixer is preferably used as a mixedpolymerizable monomer preserving container as it is.

A mixed polymerizable monomer preserving container is preferably made ofa resin and is preferably made of polyethylene. Further, a mixedpolymerizable monomer preserving container is preferably translucent andis preferably excellent in a shading property. More preferably, a mixedpolymerizable monomer preserving container has shading rate of no lessthan 99.99%. The shading rate of no less than 99.99% may be reproducedby using an aluminum foil for enhancing a shading property. A mixedpolymerizable monomer preserving container is preferably a hermeticcontainer.

A preserving temperature of the mixed polymerizable monomer preservingcontainer is at 1-35° C., and is preferably at 1-10° C. in a dark andcool place. A preserving period of a mixed polymerizable monomerpreserving container is for 10 days-1.5 years, preferably for 30 days-1year.

A mixed polymerizable monomer may be stabilized by preserving to obtaina uniformly mixed polymerizable monomer. Further, a kneading period maybe shortened and a stable paste may be prepared. When a preservingperiod is over 1.5 years, deterioration of a mixed polymerizable monomeroccurs and a mixed polymerizable monomer becomes a non-uniform state.When a preserving period is within one year, deterioration of a mixedpolymerizable monomer is not observed and a uniform mixed polymerizablemonomer may be obtained and a stable composite material may be prepared.

The mixed polymerizable monomer preserving step preferably includes amixed polymerizable monomer evaluation step. A defective semi product isdetected by inspecting a semi product in a manufacturing process toincrease a manufacturing yield of a final product.

A mixed polymerizable monomer evaluation step performed in a mixedpolymerizable monomer preserving step is a step of evaluating the mixedpolymerizable monomer formed in the mixed polymerizable monomerpreserving step. After the mixing in the mixed polymerizable monomerpreparing step, the mixed polymerizable monomer is divided, and aportion of the mixed polymerizable monomer is placed in a mixedpolymerizable monomer evaluation container that is different from amixed polymerizable monomer preserving container. A mixed polymerizablemonomer may be divided directly from the mixed polymerizable monomerpreserving container. A mixed polymerizable monomer is preferablydivided into the mixed polymerizable monomer evaluation containerimmediately after a mixed polymerizable monomer preparing step. When amixed polymerizable monomer is divided from the mixed polymerizablemonomer evaluation container right away, a evaluation of a mixedpolymerizable monomer may be more likely to be performed withoutproblems.

In the mixed polymerizable monomer evaluation step, a differentialscanning calorimetry (DSC) test, a hardening test, and/or a fluiditytest or the like is preferably performed. Each test is performed by ameasurement method known in the art to determine the acceptance orrejection. Acceptance or rejection is determined based on whether thetest result is within a predetermined range. A detailed test method ofthe hardening test, and the fluidity (flow) test will be described in“characteristic confirmation test method” below.

Although the predetermined range is important for determining thestability of the mixed polymerizable monomer, the predetermined range iswidely changed depending on the species of the mixed polymerizablemonomer etc.

By evaluating the divided mixed polymerizable monomer in the mixedpolymerizable monomer evaluation container, the mixed polymerizablemonomer preserved in the mixed polymerizable monomer preservingcontainer may be evaluated.

The composite material preparing step includes a step of kneading themixed polymerizable monomer and the silanated filler to prepare thecomposite material. The mixing method is not particularly limited. It isnecessary that the composite material prepared in the composite materialpreparing step is in a uniform state after mixing.

An ordinary kneading machine may be used as a kneader. Preferably, akneader (Inoue Seisakusho Co., Ltd etc) is used for preparing a highviscosity composite material, and a planetary mixer (Inoue SeisakushoCo., Ltd etc) is used for preparing a low viscosity composite material.

Although a kneading container accompanies a kneading machine, the volumeof a kneading container is 0.5-50 liters, preferably 2-20 liters.

A charging amount for a kneading machine is 30-70% of the volume of thekneading machine, preferably 40-60% of the volume of the kneadingmachine. When there are many charging amounts or small charging amounts,a kneading is not properly performed to generate a uniform compositematerial.

Depending on intended pasty property, a ratio for charging the mixedpolymerizable monomer and the silanated filler are 0.1-9 parts by weightof the silanated filler and 0.01-0.2 parts by weight of a particulatefiller, based on 1 part by weight the mixed polymerizable monomer.

More specifically, the mixed polymerizable monomer is 1-3 liters, thesilanated filler is 1-6 kg, and the particulate filler is 30-500 g. Thecomposite material preparing step includes a kneading step, and adefoaming step, and a more detailed embodiment is described below.

The composite material preparing step includes a step of charging thesilanated filler after charging the mixed polymerizable monomer into thekneading container, and then a step of performing the kneading step andthe defoaming step. The kneading step is a step of performing a kneadingwork, and the defoaming step is a step of performing a defoaming work.

It is important that the mixed polymerizable monomer is charged beforecharging the silanated filler, thereby shortening the kneading period toprevent the generation of variation.

The composite material is preferably prepared using the particulatefiller. In this case, the composite material preparing step includes astep of charging the particulate filler after charging the mixedpolymerizable monomer, a step of performing a particulate fillerkneading step, a defoaming step after kneading the particulate filler, astep of charging the silanated filler, and a step of performing asilanated filler kneading step and a defoaming step after kneading thesilanated filler. Kneading may be facilitated by separating the chargingthe particulate filler and the silanated filler into multiple times.When the charging of the silanated filler is divided into multipletimes, although the defoaming may be performed after kneading everytime, the defoaming is preferably performed after charging all silanatedfillers.

Kneadability of the particulate filler with the mixed polymerizablemonomer is poor. Therefore, the particulate filler and the mixedpolymerizable monomer sometimes are not kneaded enough. In some cases, aparticulate filler kneading confirmation step is preferably performed,which confirms that the kneaded product prepared by the particulatefiller kneading step and the defoaming step after particulate fillerkneading has transparency, and the kneaded product was sufficientlykneaded and defoamed. If the composite material is prepared without theparticulate filler kneading confirmation step, there may be a part wherethe particulate filler was not sufficiently mixed. It may cause avariation in the final product of the composite material. Further, it isdifficult to obtain a stable paste if there is a variation caused byinsufficient mixing. It is not preferable that the silanated filler ischarged before the kneading of an ultrafine particle filler, because itis difficult to perform a particulate filler kneading confirmation step.The silanated filler is preferably charged after the kneading theultrafine particle filler.

It is necessary to knead the mixed polymerizable monomer and theultrafine particle filler until the whole is in the uniform state. Ifthe paste has transparency after a defoaming step after kneading theparticulate filler, the paste may be considered to be uniform. When itis not uniform, the kneading and the defoaming are repeated. Ifnon-transparent ultrafine particle filler remains in the kneaded paste,it is necessary to remove a part where the non-transparent ultrafineparticle filler remains, or to stop producing the kneaded product.Similar work can be performed if the paste is semitransparent, even ifthe paste is not completely transparent.

In the silanated filler kneading step, the silanated filler is kneadedwith the mixed polymerizable monomer or the kneaded product of the mixedpolymerizable monomer and the ultrafine particle filler until becoming auniform paste. In the defoaming step, air bubbles in the compositematerial are removed. Therefore, defoaming is preferably performed whilemixing them.

It is necessary to perform a defoaming step after kneading the silanatedfiller for defoaming air bubbles in the composite material. Thedefoaming step is preferably a step of defoaming air bubbles by reducingthe vacuum to 5-200 Torr in the kneading container. In this defoamingstep, air bubbles in the composite material expand thereby causingfoaming of the composite material. The defoaming step is generallyperformed while kneading in order to break the air bubbles. A kneadingspeed for breaking air bubbles is preferably adjusted in accordance withthe braking condition of air bubbles. A kneading condition is preferablydetermined by adjusting kneading speed with depression speed. Thekneading is preferably performed while adjusting a degree ofdepressurization

The kneading period and the kneading temperature may be optionally set.For example, it is preferable to perform the particulate filler kneadingstep at a kneading temperature 5-60° C. for a kneading period 5-30minutes after charging the particulate filler, the defoaming step afterkneading the particulate filler at a vacuum degree of 5-200 Torr of fora kneading period 5-30 minutes, the silanated filler kneading step at akneading temperature of 5-60° C. for kneading period of 5-40 minutesafter charging the silanated filler, and the defoaming step afterkneading the silanated filler at a vacuum degree of 5-200 Torr for akneading period 5-30 minutes.

When the polymerization initiator is a chemical polymerizationinitiator, low temperature mixing is preferred. In this case, thekneading step is preferably performed at a kneading temperature of 1-25°C., 1° C.-room temperature, or 5-23° C. for a kneading period of 5-30minutes, in this case. Further, in the defoaming step, the kneading isperformed at a kneading temperature of 1-25° C., 1° C.-room temperature,or 5-23° C. for a kneading period of 5-30 minutes at a vacuum degree of60-200 Torr.

These kneading periods and kneading temperature differ depending on thespecies of the kneader or the planetary mixer.

The composite material preserving step includes a step of preserving thecomposite material prepared in the composite material preparing step.

The composite material is preserved in the composite material preservingcontainer. The volume of composite material preserved in in thecomposite material preserving container is 1-50 cc, and preferably 2-5cc. with is 1-8 liters, is preferably 2-5 liters.

The composite material is divided into the composite material preservingcontainer from the mixing container that is used in the compositematerial preparing step.

The composite material preserving container is preferably made of aresin and is preferably made of polyethylene. Further, the compositematerial preserving container is preferably translucent and ispreferably excellent in shading property. More preferably, the compositematerial preserving container has shading rate of no less than 99.99%.The shading rate of no less than 99.99% may be reproduced by using analuminum foil for enhancing a shading property. The composite materialpreserving container is preferably a hermetic container.

The preserving temperature of the composite material preservingcontainer that preserves the composite material prepared by thecomposite material preparing step, is at 1-25° C., and is preferably at1-8° C. in a dark and cool place. The preserving period of the compositematerial preserving container that preserves the composite materialprepared by the composite material preparing step is 10 days-1.5 years,is preferably 30 days-1 year.

The composite material is stabilized by preserving to obtain thecomposite material having a uniformly pasty property. When a preservingperiod of the composite material preserving container is over 1.5 yearsfrom a point of time when the composite material is filled in thecomposite material preserving container, a preserving period of thesmall quantity preserving container used by dentists and dentaltechnicians, which are the final user, becomes shorter because thedeterioration of the composite material occurs and the pasty property ofthe composite material is in a non-uniform state. When the preservingperiod is within one year from a point of time when the compositematerial is filled in the composite material preserving container, thedeterioration of the composite material is not observed and thecomposite material that is a uniform may obtain and a paste having astable pasty property may be prepared.

The composite material preserving step preferably includes a compositematerial evaluation step. A defective semi product is detected byinspecting a semi product in a manufacturing process to increase amanufacturing yield of a final product.

The composite material evaluation in the composite material evaluationstep may be performed as follows. After kneading of the compositematerial preparing step, a portion of the composite material is dividedinto the composite material evaluation container that is different fromthe composite material preserving container. The composite material ispreferably divided into the composite material evaluation containerimmediately after the kneading of the composite material preparing step.When the composite material is directly divided from the kneadingcontainer, the evaluation of the composite material may be more likelyto be performed without problems.

In the composite material evaluation step, a differential scanningcalorimetry (DSC) test, a hardening test, and/or a fluidity test or thelike is preferably performed. Each test is performed by a measurementmethod that is known in the art to determine the acceptance orrejection. Acceptance or rejection is determined based on whether thetest result is within a predetermined range. Although the predeterminedrange is important for determining the stability of the compositematerial, the predetermined range may be widely changed depending on thespecies of the composite material etc. A detail test method of ahardening test, and a fluidity (flow) test will be described in“characteristic confirmation test method” below.

By evaluating the divided composite material from the composite materialevaluation container, the composite material in the composite materialpreserving container may be evaluated. The composite material fillingstep includes a step of filling the composite material preserved in thecomposite material preserving container into a small quantity preservingcontainer.

The small quantity preserving container is a container that may be usedon the end user side, and is generally called a syringe container. Thevolume of the syringe container is in a range of 1-200 cc. When usingthe composite material having a low viscosity, a syringe container maybe a cylindrical injector type and the composite material maybedischarged from the tip nozzle of the cylindrical injector type bypushing a stick. When using the composite material having a highviscosity, a syringe container may be a cylindrical injector type as isthe case in a low viscosity, but the composite material may bedischarged by screwing a stick. A small quantity syringe container maybe a compule, which is a single use container for cavity-filling. All ofthese containers are a cylindrical container that discharge thecomposite material pushed by a piston. When a composite materialdischarging port of the cylindrical container is sharpened, the effectof composite material is remarkable.

The composite material is preserved in a small quantity preservingcontainer. The volume of mixed polymerizable monomer in the smallquantity preserving container is 1-50 cc, and preferably 2-5 cc.

The small quantity preserving container is preferably made of resin, ismore preferably made of polyethylene.

Further, the small quantity preserving container is preferablytranslucent and is preferably excellent in shading property. Morepreferably, the small quantity preserving container has shading rate ofno less than 99.99%, and is a hermetic container.

The composite material may be pushed out by pushing the stick of thecylinder and/or may be pushed out by screwing the stick according toviscosity of the paste. The composite material preserving container maybe an electric cylindrical container or a desktop cylindrical container.

The filling method from the composite material preserving container tothe small quantity preserving container may be by the existing method.

The composite material may be filled by a filling machine that may be afilling machine that is known in the art.

The following describes an example of a filling machine.

The filling machine comprises a feeder into which a composite materialis charged, and a nozzle that discharges a composite material. Acomposite material charged into the feeder is discharged from the nozzleto be filled in the small quantity preserving container. A pistonmechanism or a screw feeder may be used as the feeder.

In charging the composite material preserved in the composite materialpreserving container into the filling machine, a plurality of compositematerials preserved in the composite material preserving container arecharged into the filling machine. Therefore, air bubble mixing into aconventional composite material are observed. It was found that the airbubbles may be reduced and/or prevented by the composite materialdescribed herein, that may be formed using the composite materialpreserving step and the small quantity preserving container preservingstep described above.

The composite material may be heated during filling, preferably may beheated to 15-45° C.

The small quantity preserving step includes a step of preserving thecomposite material filled in the composite material filling step in thesmall quantity preserving container for a pre-determined period.

The preservation temperature of the small quantity preserving containeris at 1-40° C., and is preferably at 1-25° C. in a dark and cool place.The preserving period of the small quantity preserving container is for50 days-5 years, is preferably 100 days-3 years.

The composite material is stabilized by preservation to obtain thecomposite material that is a uniform and has a stable pasty property.When a preservation period is over five years, deterioration of thecomposite material occurs and the pasty property of the compositematerial is in a non-uniform state. When a preservation period is withinfive years, deterioration of the composite material is not observed andobtains the composite material that is a uniform and has a stable pastyproperty.

The small quantity preserving container preserving step preferablyincludes a final evaluation step. The final product in a productionprocess is inspected to confirm adaptability for shipping.

The final evaluation in the final evaluation step is a evaluation of thecomposite material performed in the small quantity preserving containerpreserving step. After the composite material filling step, an arbitrarysmall quantity preserving container among many small quantity preservingcontainers is evaluated.

In the composite material evaluation step, a differential scanningcalorimetry (DSC) test, a hardening test, and/or a fluidity test or thelike is preferably performed. Each test is performed by a measurementmethod known in the art to determine the acceptance or rejection.Acceptance or rejection is determined based on whether the test resultis within a predetermined range. Although the predetermined range isimportant for determining the stability of the composite material, thepredetermined range is widely changed depending on the species of thecomposite material etc. A detailed test method of a hardening test, anda fluidity (flow) test will be described in “characteristic confirmationtest method” below.

The composite material may be shipped in the small quantity preservingcontainer to be used by dentists and dental technicians that are theuser of the composite material.

A characteristic confirmation test method for confirming an effect ofthe the composite material is described below. Also specific testmethods of testing items of a mixed polymerizable monomer evaluatingitem and a composite material evaluating item is described below.

Viscous test: This test is also a mixed polymerizable monomer evaluatingitem

The mixed polymerizable monomer of 250 g was charged in a brown glasscontainer and was left in a constant temperature room of 23+−1° C. for24 hours. Then a viscosity value of the mixed polymerizable monomer ismeasured by using B type viscometer (BL type No. 3 rotor) after 5minutes. A viscosity value of 5000-10000 mPa·S is necessary, and it ispreferable to be viscosity value of 7000-9000 mPa·S. If the viscosityvalue is within the above ranges, good paste may be obtained.

-   -   Evaluation Criteria:        -   A: sufficiently mixed and no unevenness        -   B: insufficiently mixed and generating dissolution            Hardening test: This test is also a mixed polymerizable            monomer evaluating item and a composite material evaluating            item

A mixed polymerizable monomer or a composite material is filled in ametal mold with a hole having a thickness of 2 mm and diameter of 15 mm.A surface of the filled mixed polymerizable monomer or compositematerial is pressed into contact with a transparent plate glass andcured by an optional polymerization method. For example, the filledmixed polymerizable monomer or the filled composite material in themetal mold was exposed to light for 180 seconds using SOLIDILIGHT II(Shofu Inc.) to be cured. The Vickers hardness (kgf/mm²) of the curedproducts was measured by the following measuring method.

The transparent plate glass being pressed into contact with the filledmixed polymerizable monomer or composite material was removed. TheVickers hardness on the surface of the cured products, which was pressedinto contact with a transparent plate glass, was measured using a microhardness tester (made by Akashi Seisakusyo K.K., merchandise code:“MVK-E”) in 200 g load for 10 seconds. Measurement is performed 3 timesin different positions and the average value of the 3 measurement timesis defined as the Vickers hardness of the cured products.

Transmittance

The hardened material was prepared by the same preparation method ashardening test. Transmittance of the hardened material was measured inthe wavelength range between 780 nm and 380 nm by means ofspectrophotometer U-3200 (made by Hitachi Seisakusyo K.K.).Transmissivity of more than 95% is necessary, and it is preferable to betransmissivity of more than 99%.

Property/Visual Test

The composite material preserved in the composite material preservingcontainer was taken out at a surface of the composite material and aninner portion of the composite material in composite material preservingcontainer, and was scratched with a resinous spatula. Each of fivedental technicians confirmed match state of the surface. The mostfrequent grade was set as the result of evaluation.

-   -   Evaluation Criteria:        -   A: Scratched portion of surface composite material with a            resinous spatula showed luster. The silanated filler matched            with a polymerizable monomer well at the scratched portion            of surface composite material. Scratched portion of inner            composite material with a resinous spatula showed luster.            The silanated filler matched with a polymerizable monomer            well at inner scratched portion.        -   B: Scratched portion of surface composite material with a            resinous spatula showed slight luster. The silanated filler            matched with a polymerizable monomer at the scratched            portion of surface composite material. Scratched portion of            the inner composite material with a resinous spatula showed            luster. The silanated filler matched with a polymerizable            monomer at inner scratched portion.        -   C: Scratched portion of surface composite material with a            resinous spatula became slight white. The silanated filler            matched with a polymerizable monomer at the scratched            portion of surface composite material. Scratched portion of            inner composite material with a resinous spatula showed            luster. The silanated filler matched with a polymerizable            monomer well at inner scratched portion. The property is            different between the surface sample and the inner sample.        -   D: Scratched portion of surface composite material with a            resinous spatula became white. The silanated filler did not            match with a polymerizable monomer at the scratched portion            of surface composite material. Scratched portion of inner            composite material with a resinous spatula showed slight            luster. The silanated filler matched with a polymerizable            monomer at inner scratched portion. The property is            completely different between the surface and the inner            sample.            Small Amount Property/Visual Test

All composite material preserved in the small amount preservingcontainer for 120 days are forced out. The composite material wasscratched with a resinous spatula. Each of five dental techniciansconfirmed match state of the surface. The most frequent grade was set asthe result of evaluation.

-   -   Evaluation Criteria:        -   A: Scratched portion of composite material with a resinous            spatula showed luster. The silanated filler matched with the            polymerizable monomer well at the scratched portion.        -   B: Scratched portion of composite material with a resinous            spatula showed slight luster. The silanated filler matched            with a polymerizable monomer at the scratched portion.        -   C: Scratched portion of composite material with a resinous            spatula became slight white. The silanated filler matched            with a polymerizable monomer at the scratched portion.        -   D: Scratched portion of composite material with a resinous            spatula became white. The silanated filler did not match            with a polymerizable monomer at the scratched portion of            surface composite material.            Evaluation of Property Variation Between Lots

Twenty composite materials preserved in small quantity preservingcontainers for 120 days were prepared. The same test as the small amountproperty/visual test described above is performed to evaluate a propertyvariation.

The results of this evaluation show a comparison with extruded compositematerial with regard to the property/visual test. Therefore, it is aprerequisite that the results of this evaluation is within the result ofthe small amount property/visual test. The evaluations show whether theproperty is sensuously different between the small quantity preservingcontainers within the result of the small amount property/visual test.

More specifically, for example, when evaluation criteria of the smallamount property/visual test is “A: Scratched portion of compositematerial with a resinous spatula showed luster. The silanated fillermatched with a polymerizable monomer well at the scratched portion,” itis a prerequisite that all evaluation criteria of the 20 small quantitypreserving containers is “A,” and the evaluations show whether asensuously difference of the property is observed between 20 smallquantity preserving containers.

-   -   Evaluation Criteria:        -   A: Observed no variation in all of 20 small quantity            preserving container.        -   B: Observed variation in five or less small quantity            preserving container among 20 small quantity preserving            container        -   C: Observed variation in six or more small quantity            preserving container among 20 small quantity preserving            container            Evaluation of Property Variation in Syringe

One small quantity preserving container preserved for 120 days wasprepared. All composite material preserved in the small amountpreserving container was forced out and was divided into 4 parts.

The same test as the small amount property/visual test described aboveis performed to evaluate a property variation.

The results of this evaluation show a comparison with extruded compositematerial with regard to the property/visual test. Therefore, it is aprerequisite that the results of this evaluation is within the result ofthe small amount property/visual test. The evaluations show whether theproperty is sensuously different in the small quantity preservingcontainer within the result of the small amount property/visual test.

-   -   Evaluation Criteria:        -   A: Observe no variation        -   B: Observe substantially no variation        -   C: Observe variation            Bubbles Mixing Test

One small quantity preserving container preserved for 120 days wasprepared. All composite material preserved in the small amountpreserving container is forced out. Then the composite material wasexposed to light for 180 seconds using SOLIDILIGHT II (Shofu Inc.), andwas cut every 1 millimeter to confirm presence of bubbles.

-   -   Evaluation Criteria:        -   A: No bubbles were observed        -   B: Small bubbles were observed without problem in use        -   C: Big bubbles were observed with problem in use            Fluidity Test: This test is a mixed polymerizable monomer            evaluating item and a composite material evaluating item

The composite material of 0.5 ml is placed on a glass plate. Another oneof a glass plate that is the same as the above is placed on thecomposite material. A weight is placed on the glass plate. The totalweight of the weight and the glass plate where the weight is placed is400 g. Ten minutes after placing the weight, the weight is removed. Thecomposite material was exposed to light for 180 seconds usingSOLIDILIGHT II (Shofu Inc.). Image analysis was performed by a personalcomputer to compute the spread area (mm²). The obtained spread area isthe flow value. A larger flow value indicates that the fluidity issuperior. This test is performed ten times to calculate a standarddeviation(mm²) of ten test samples.

Intermittency Extrusion Test

The composite material was gathered by 0.5 ml once in 24 hours. Afterthat without delay, a fluidity test was performed to evaluate avariation of the numerical value of the fluidity of the compositematerial gathered once in 24 hours.

-   -   Evaluation Criteria:        -   A: a variation of the numerical value is small (less than 1            mm)        -   B: a variation of the numerical value is large (1 mm or            more)        -   C: incapable of pushing out on the way.

EXAMPLES

The following shows the names and abbreviations of the components usedin the examples and the comparative examples.

Polymerizable Monomer

-   Bis-GMA:    2,2-bis(4-(3-(meth)acryloyloxy-2-hydroxypropoxy)phenyl)propane, 60    pts. wt.-   UDMA: di(methacryloxyethyl)trimethylhexamethylenediurethan, 70 pts.    wt.-   TEGDM: triethyleneglycol-dimethacrylate, 30 pts. wt.-   3G: triethyleneglycol(meth)acrylate, 40 pts. wt.-   HEMA: 2-hydroxyethyl methacrylate,    Polymerizable Monomer Bearing Phosphate Ester Group-   2-MEP: 2-(methacryloxy)ethyl phosphate-   Bis-MEP: bis[2-(methacryloyloxy)-ethyl]phosphate-   6-MHPA: 6-(methacryloxy)hexyl phosphonoacetate    Polymerizable Monomer bearing Dibasic Acid Carboxyl Group-   4-AET: 4-Acryloxyethyltrimellitic acid-   4-MET: 4-Methacryloxyethyltrimellitic acid    Filler-   ASG filler: Aluminosilicate glass filler (average particle diameter    of 5 μm)-   FASG filler: Fluoroaluminosilicate glass filler (average particle    diameter of 1.8 μm)-   Ultrafine Particle Filler-   R-972    Polymerization Accelerator-   BBA⋅.Na: a sodium salt of 5-n-butylbarbituric acid-   EB: p-N,N-Ethyl-dimethylaminobenzoate 1 pts. wt.-   OT: Dioctyltin dilaurate 2 pts. wt.    Polymerization Initiator-   CQ: Camphorquinone    Polymerization Inhibitor-   BHT: Butylated hydroxytoluene

The composite materials were prepared from materials shown in FIG. 1,under the condition shown in FIG. 1. The details are below.

Preparing Mixed Polymerizable Monomer

The polymerizable monomer and the polymerization initiator shown in FIG.1 were mixed by mixer (Aikosha Inc.: BM) which uses a blade for mixingor a tumbler mixer (Seiwa Giken Inc.: TM). FIG. 1 shows mixing periodsand mixing temperatures.

Among the numerical value of components of polymerizable monomer shownin FIG. 1, the numerical value of polymerization inhibitor (BHT) showsthe adding amount with respect to 100 pts.wt. total amount of componentsof polymerizable monomer other than polymerization inhibitor (i.e.polymerization inhibitor is an externally content).

Preserving Mixed Polymerizable Monomer

After mixing, mixed polymerizable monomer is filled in the mixedpolymerizable monomer preserving container (the capacity is 10 liters)having shading rate of no less than 99.99% and being a bottle typecontainer with a lid and is preserved at 23° C.

Evaluation Mixed Polymerizable Monomer

A fluidity test, a hardening test, and a transmittance measurement areperformed with respect to the preserved mixed polymerizable monomer. Thetest results are shown in FIG. 1.

Silantion Method

Silane Treatment Liquid:

-   -   Silane treatment liquid a: 3% of        γ-methacryloyloxypropyltrimethoxysilane as silane coupling        agent, 77% of ethyl alcohol, and 20% of water.    -   Silane treatment liquid b: 30% of        γ-methacryloyloxypropyltrimethoxysilane as silane coupling        agent, 69% of ethyl alcohol, and 1% of water.

A filler of 10 kg was heated and treated with 10 kg of “silane treatmentliquid a” or 2 kg of “silane treatment liquid b”. The silane treatmentliquids were sprayed and were mixed for about 90 minutes in a treatmentcontainer with string. FIG. 2 and FIG. 3 shows which mixing machine isused. After mixing, the silanated filler was aged at 50° C. for 40hours. Then, the temperature was raised and kept at 120° C. Next, thesilanated filler was cooled to obtain silanated filler aggregates. Theaggregates were charged in a Henschel mixer and was crushed at 1800 rpmfor 5 minutes to prepare silanated fillers “a” and “b,” of which thesurfaces are coated with a poly(organo) siloxane.

Silanted Preserving Method

The silanated fillers of which the surfaces are coated with apoly(organo) siloxane are preserved in a polyethylene bag in 25 kg unitsat 10-25° C. for the preserving period as shown in FIG. 1.

Preparing Composite Material

The silanated filler and mixed polymerizable monomer preserved as shownFIG. 1. were mixed in an amount as shown FIG. 2 and FIG. 3 by a kneader(Inoue Seisakusho Co., Ltd: ND) or a planetary mixer (Inoue SeisakushoCo., Ltd: PM). The mixed polymerizable monomer is charged first. Thecomposite material is prepared by mixing under the conditions as shownFIG. 2 and FIG. 3.

Preserving Composite Material in Composite Material Preserving Container

The composite material is filled in the composite material preservingcontainer (the capacity is 4 liters) having a shading rate of no lessthan 99.99% and being a tray type container with a lid and is preservedunder the conditions as shown FIG. 2 and FIG. 3.

Evaluating Composite Material

A hardening test and a property/visual test are performed with respectto the preserved composite material. The test results are shown in FIG.2 and FIG. 3.

Filling Composite Material into Small Amount Preserving Container

The composite material in the composite material preserving container ischarged into a cylinder of a filling machine. The cylinder is set on thenozzle of the filling machine. Three grams of the composite material isfilled in a cylinder, which is as small amount preserving container, bya piston mechanism of the filling machine. For more detail, all of thecomposite material in the cylinder of a filling machine is filled in thecylinders as small amount preserving container. After that, thecomposite material in another composite material preserving container iscontinuously filled in the cylinder of a filling machine to continue thefilling to the cylinders as small amount preserving container therebyobtaining the 2000 cylinder, which is as small amount preservingcontainer, filled with small amount composite material. The cylindersare attached with a stick, a nozzle, a cap or the like to completefilling to the small amount preserving container.

After filling to the small amount preserving container, small amountproperty/visual test, evaluation of property variation between lots,evaluation of property variation in syringe, bubbles mixing test,fluidity test, and intermittently extrusion test were performed.

The test results are shown in FIG. 2 and FIG. 3. In a paste prepared bythe method described herein, a change in properties was not observed in120 days to 3 years. A change in properties was somewhat observed, butthe pasty property remained stable for 3 years-5 years. Within 60 days,a pasty property was not stable and a significant change is propertieschange was observed. After 5 years, a significant change in propertieschange was observed.

The mixing method described herein provides stability of the propertiesfor 60 days-5 years, preferably for 120 days-3 years. FIG. 4 shows thedifference of the fluidity test result during the small amountpreserving between the acceleration at the present time and the lasttime. It is shown that the composite material described herein isstable. Regarding the “difference,” the column “60 days after” shows thedifference between immediately after filling and 60 days after filling,the column “120 days after” shows the difference between after 60 daysand after 120 days, the column “3 years after” shows the differencebetween after 120 days and after 3 years, the column “5 years after”shows the difference between after 3 years and after 5 years, the column“6 years after” shows the difference between after 5 years and after 6years. The differences of the composite materials described herein arewithin 100 mm² and keep a stable fluidity. The differences of thecomparative composite materials are over 100 mm² and do not keep astable fluidity.

Although the preceding description has been described herein withreference to particular methods, materials and embodiments, it is notintended to be limited to the particular methods, materials andembodiments disclosed herein; rather, it extends to all functionallyequivalent methods, materials and uses, such as are within the scope ofthe claims.

The invention claimed is:
 1. A method for manufacturing a compositematerial comprising a silanated filler, a polymerizable monomer, and apolymerization initiator, the method comprising, in order, a mixedpolymerizable monomer preparing step, a mixed polymerizable monomerpreserving step, a composite material preparing step, a compositematerial preserving step, a composite material filling step, and a smallquantity preserving container preserving step, wherein: the mixedpolymerizable monomer preparing step comprises charging thepolymerization initiator into the polymerizable monomer in a mixingcontainer, and mixing the polymerizable monomer and the polymerizationinitiator at a mixing temperature of 1-60° C. for a mixing period of 1minute-24 hours to prepare a mixed polymerizable monomer, the mixedpolymerizable monomer preserving step comprises preserving 1-50 litersof the mixed polymerizable monomer prepared in the mixed polymerizablemonomer preparing step at a preserving temperature of 1-23° C. for apreserving period of 10 days-1.5 years, the composite material preparingstep comprises performing a kneading step and a defoaming step, whereinthe kneading step comprises kneading the mixed polymerizable monomer andthe silanated filler at a kneading temperature of 5-60° C. for akneading period of 5-40 minutes after charging the silanated filler intothe mixed polymerizable monomer, wherein a ratio of the silanated fillerto the mixed polymerizable monomer is 0.1-9 parts by weight of thesilanated filler to 1 part by weight of the mixed polymerizable monomer,and the defoaming step comprises defoaming the mixed polymerizablemonomer and the silanated filler at 5-200 Torr for a defoaming period of5-30 minutes to prepare a composite material, the composite materialpreserving step comprises preserving 1-8 liters of the compositematerial prepared in the composite material preparing step at apreserving temperature of 1-25° C. for a preserving period of 10days-1.5 years, the composite material filling step comprises fillingthe composite material preserved in the composite material preservingstep by extrusion from a nozzle of a filling machine into a smallquantity preserving container having 1-50 cc of volume, and the smallquantity preserving container preserving step comprises preserving thecomposite material filled in the composite material filling step in thesmall quantity preserving container at a preserving temperature of 1-40°C. for a preserving period of 50 days-5 years.
 2. The method formanufacturing a composite material according to claim 1, wherein themethod further comprises, between the mixed polymerizable monomerpreserving step and the kneading step of the composite materialpreparing step, a particulate filler kneading step that compriseskneading the mixed polymerizable monomer and a particulate filler at akneading temperature of 5-60° C. for a kneading period of 5-30 minutesafter charging the particulate filler into the mixed polymerizablemonomer, wherein a ratio of the particulate filler to the mixedpolymerizable monomer is 0.01-0.2 parts by weight of the particulatefiller to 1 part by weight of the mixed polymerizable monomer, and aparticulate filler defoaming step after the particulate filler kneadingstep that comprises defoaming the mixed polymerizable monomer and theparticulate filler at 5-200 Torr for a defoaming period of 5-30 minutes,wherein the mixture obtained from the particulate filler kneading stepand the particulate filler defoaming step is utilized in the subsequentcomposite material preparing step, wherein the particulate filler iskneaded with the mixed polymerizable monomer and the silanated filler inthe kneading step of the composite material preparing step, wherein theparticulate filler is defoamed with the mixed polymerizable monomer andthe silanated filler in the defoaming step of the composite materialpreparing step, and wherein the composite material prepared in thedefoaming step of the composite material preparing step comprises theparticulate filler, the silanated filler, the polymerizable monomer, andthe polymerization initiator.
 3. The method for manufacturing acomposite material according to claim 1, wherein the mixed polymerizablemonomer preserving step comprises a mixed polymerizable monomerevaluation step of evaluating a portion of the mixed polymerizablemonomer.
 4. The method for manufacturing a composite material accordingto claim 1, wherein the composite material preserving step comprises acomposite material evaluation step of evaluating a portion of thecomposite material.